If he wouldn't have thrown in the 'dark or tunnel' issue, this might be the case, but a door switch wouldn't cause this.No it is not normal.
You may have a faulty door switch and the system thinks a door is ajar.
P.S.Hi. I bought an 08 Optima, used, from the USA. I live in Ghana. I had a similar problem. There are about 3 wires feeding the interior light unit I think. i disconnected one and it stopped. I have since sold the car so cannot verify which wire, but it stopped and all was working correctly.